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23

RGB is a additive, projected light color system. All colors begin with black "darkness", to which different color "lights" are added to produce visible colors. RGB "maxes" at white, which is the equivalent of having all "lights" on at full brightness (red, green, blue). CMYK is a subtractive, reflected light color system. All colors start with white ...


13

LAB (aka CIELAB), space is quite useful. It's good for exaggerating color differences, relating colors to color opponent theory. I do a lot of image enhancement and digital art creation from photographs in CIELAB or spaces that resemble it. Its main advantages are separation of color from brightness and roughly evenly spread out color changes - two ...


10

CMYK and RGB are the two colour spaces, methods of creating colour. CMYK is subtractive, like paint/pigment. you start with nothing (white paper) and as you add more colours it eventually turns black. CMYK represents the standard coloured inks that printers use to create colours: cyan, magenta, yellow and black. RGB is additive, the way light creates ...


9

The short answer is that you can't reasonably ensure that colors are going to look good on all, or even a wide variety of, display devices. The long answer is that this is possible but there are a number of caveats: You need to invest in color-calibration devices and the truly good ones don't come cheap For internal use, you would also need to strictly ...


8

Color values are quantized by the bit depth of the format used to store the data. For example, in most standard formats and modern displays there are eight bits per color, per pixel, sometimes referred to as 24-bit True Color. There are 2^8 = 256 levels, which is why RGB colors are typically represented by three values in the range 0 to 255. Unless the ...


7

It's actually far simpler than it may first appear. The bottom line is that it's best to convert to the most native format as early as possible. Full colour printing typically uses four inks to create a photorealistic image. In theory, cyan, magenta and yellow should be enough to print a high quality image, but adding black aids the printing process, giving ...


7

RGB is an additive spectrum... you ADD colors to get white. Dkuntz is correct stating that RGB is light-based. It is. It uses the visible light spectrum to display colors. CMYK is a subtractive spectrum... you REMOVE color to get white. DKuntz's use of the term "color-based theory" is really nonsensical. Since RGB is also a color spectrum. A more ...


7

You could use Lab colour space to find your matches. Colours with the same L value as your target gray will look nearly identical when converted to grayscale. For example, a Lab gray of (50, 0, 0), will look very similar to the Lab reds (50, 30, 0), (50, 50, 30), and (50, 50, 50) when converted to grayscale. Samples below use Photoshop (Image > Mode > ...


7

RGB is a color space that can only exist with projected light. It's physically impossible to replicate it on paper, which is a reflected light color space. So no, no printing press can 'print RGB'. At best, prepress RIP software can convert from RGB to CMYK. In fact, this is what most prepress software workflows do. How they convert to CMYK can vary ...


6

HSV (also called HSB) is based on the RGB system - it's actually just a transformation of the RGB color space (so it's still additive, and is intended for computer displays). The three components of this color system are: H: Hue. This is the angle on the color wheel. Starting with red at 0 degrees. S: Saturation. This is the ammout of 'color' in the color. ...


6

You'll want to scale first. Downsizing the image will compress your palette to some extent in and of itself. Indexing before hand would throw color away that may be helpful in the down-sampling step.


6

My guess is that your document colours are set to grayscale. Go to the colour panel, click the little down-arrow in the top right corner, and change there:


6

RGB color is for light-producing situations, and is additive, which means that you are adding light of one color to light of another color, resulting in more light and a mixed color. CMYK color is for light-absorbing situations, and is subtractive, which means that you are absorbing light instead of reflecting it, and mixing two pigments results in ...


5

Projectors are crap. It's not an issue of picking the right color, it's just an issue of projector technology being really crappy.


5

Not to detract from Marc's excellent and comprehensive answer, there are some points that are worth a bit more explanation. It's a big subject. This gets geeky before it gets better, so bear with me and follow closely. :) CMYK and RGB are "color models," not color profiles. A color model is a way to represent colors using numbers. There are other models, ...


5

Here is a rule. If you follow it, you will be loved by your print providers and you clients! RULE: Always ask your printer (or magazine, poster or billboard publisher) for their PDF specifications before submitting artwork for print, and any other specs they might have for a particular type of job, and use their specs to the letter. A good prepress ...


5

I would scale then Index - I can't think of a technical reason why, but.. If in doubt try it both ways, it won't take long and you can compare them both afterwards to see which best fits the purpose. [added]: Scale, then index: Index, then scale:


4

A few things... You should stick with one printer if color accuracy is important. There are going to be variations on one press enough as it is, and adding a second one will just make things more exciting. The better printers I have come across will offer for free a color profile to calibrate your in-house equipment with so that you can better gauge how ...


4

It is a misnomer, or at least confusing, to say both: "RGB is based on light and it's additive because you start with no light" and "CMYK is based on ink and it's subtractive because you start with no ink". It is easy to understand how RGB works, as the usual displays create colors by adding the additive primaries, red, green and blue, together in ...


4

Your original question has been adequately answered, but since you're a photographer, it's important to recognize that there are different RGB color spaces. The three you'll most often come across in photography are "ProPhoto RGB", "Adobe RGB" and "sRGB". They all measure color using the RGB model (amounts of Red, Green and Blue light), but differ in their ...


4

The colour shift is probably not related to the bit depth (8 or 16), but more likely to the gamut of RGB vs CMYK. As far as I'm aware, when Photoshop refers to 8-bit or 16-bit colour, it's talking about each channel, so 16 bits is plenty for individual colour channels in RGB, and won't be the cause of changing colours (if it was 8-bits shared between the ...


4

Ah, after some more searching, I found it on my own! It appears I was specifically looking for Munsell chroma, CIELAB LCH's chroma, or UP Lab chroma (all basically attempts to get at the same idea). Unfortunately, converting between sRGB and Munsell chroma is non-trivial and UP Lab chroma copyrighted, but it looks like sRGB -> LCH is not too difficult.


4

Although I never heard the term 'pastel colour space', it looks like you're talking about tints, tones and shades of a hue, in HSB colour space. The term you're looking for is shade. The pure hue has S(aturation) and B(rightness) each equal to 100%. Adding any amount of white reduces saturation, while keeping the brightness at 100%, yielding a tint of the ...


3

I don't think you'll be able to accurately mimic the 16bit display without knowing more about the dithering method it uses. Some 16bit and 18bit displays animate their dither pattern, meaning they actually look better than you may expect (I believe lots of laptop displays use 18bit with an animated dither). Also, there's quite a few dithering methods ...


3

Unfortunately Philips answer is correct; that said i produce small works weekly to be displayed on both a projector and on the web and am able to make both mediums look reasonably similar. In my experience; while almost all home monitors are not colour calibrated, the variation is quite slight (as perceived by Joe Public). i.e. something that was meant to ...


3

It really depends on what technology you rely on when printing a job. Generally, numeric printing is a little to a lot darker than what you have on screen and there's no way to be sure your greens for example won't come out yellowish or your violets reddish. For numeric printing, I highly recommend to approve a sample of the job (press proof) before going ...


3

RGB is an additive color space. If you mix the three base colors (red, green and blue) you get white. That is the model monitors use, if the red light and the green light and the blue light is mixed, it becomes white. CMY (cyan, magenta and yellow) are suubtractive. If you mix all, you get black. That model is used by printers. If on a dot are printed all ...


3

If your document is currently CMYK, this requires two steps: Edit > Convert to Profile -- Set the RGB space to sRGB. Edit > Transparency Blend Space > Document RGB. For new documents, in CS5, choose "Web" for Intent, and the document will be created in RGB, with RGB swatches. Apply step 1 above if your default RGB setting is something other than sRGB.


3

Dither adds noise to smooth color gradients. From Wikipedia with added emphasises: Dither is an intentionally applied form of noise used to randomize quantization error, preventing large-scale patterns such as color banding in images. Therefore, using dither with conversion will—by definition—produce "random" results. The algorithm Photoshop uses is ...


3

So, the above advice from Nick only works for 50% Luminance. If you apply any other L value same to different colors, the gray result is different. There must be a math for that, but you can do it on-screen by-eye. If you create all the colors you want and then lay a gray element (illustrator) or layer (photoshop) with its transparency mode to "color" (or ...



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